Customers purchasing decanters require the manufacturer of the decanter to supply them with dam plates which provide a range of pond radii for satisfactory process operation. Process personnel from the manufacturer of the centrifuge machine may be required to carry many sets of plate dams in an attempt to obtain the proper radius or pond level to satisfy the customer's needs during initial operation. It is not unusual for these process personnel to carry around 30 pounds of plates. Further, if the available dams fail to produce the proper radius, there is often a delay in getting the dams fabricated to produce specific pond radii after such dimensions are ascertained or agreed upon.
The present invention provides plate dam assemblies which may be mounted directly to existing bowl hubs. One assembly embodiment provides infinite adjustment of pond radii, and other embodiments provide for predetermined incremental adjustments. These adjustments, of course, fall within the limits afforded by that particular set of plate dam assemblies selected.
Past efforts to provide a variable pond level or radius included dam members having an eccentric hole or opening therein and rotating these dams in the hub. These devices generally required the use of costly components and were incapable of providing sufficient arc length of weir surface for the volume of effluent exiting from the bowl. Insufficient dam length results in a large change in liquid radius for a change in feed rate, making performance difficult to control when the pond level must be maintained near the solids discharge radius.
Briefly, the present invention provides a retainer member which is mountable directly in a recess provided in existing hubs. The plate dam is carried in an eccentric recess formed in the rear surface of the retainer. The retainer is rotatable within the hub recess which causes the plate dam to move radially inwardly or outwardly, thus offering a weir surface which provides pond levels of varying radii. The plate dam rotates with the hub; it is not rotated within the eccentric recess of the retainer and always has its weir surfaces substantially normal to the axis of rotation of the bowl to thus coincide with the rotating pond level. Additionally, the plate dams are reversible to provide an additional weir surface to thereby increase the range of adjustability of each dam plate assembly.